Investigating Wastewater Pollution Using Laser-Induced Breakdown Spectroscopy

Abstract

Water pollution is a major concern due to increased human activities
since the early 1900s. The metal industry has been a primary source of
heavy metal contamination, resulting in the release of harmful
substances into the environment and risking living creatures through
wastewater. Standard analytical techniques like ICP-MS, ICP-OES,
FAAS, and AAS are widely used to measure harmful substances.
However, they come with drawbacks such as costly equipment and
chemicals, complex sample preparation, and time-consuming
procedures. This experiment aims to establish the LIBS experimental
setup, collect wastewater samples from industrial sites, and investigate
the presence of Pb and Cd in the wastewater using LIBS. An Nd:YAG
laser (1064nm, 50 mJ, 10ns) and spectrometer (HR4000) were used to
determine the existence of cadmium and lead in the wastewater from
the end of the sewage from the area near Steel Station, Upon Paint
factory, WCS food factory, and Yong Shing Tin factory(which is located
in Muar, Johor; Parit Jawa, Johor; Ledang, Johor; and Merlimau, Melaka
respectively). The cadmium chloride and lead acetate were used as the
reference samples to compare the LIBS spectra of the wastewater
samples. In this study, wastewater from industrial sites was analysed
using LIBS, comparing it to cadmium chloride and lead acetate
reference samples using two sampling methods i.e. using glass slide,
and using filter paper. LIBS with glass slides sampling technique
showed significant peaks indicating the presence of these elements in
reference samples, the filter paper method didn't serve as well. Besides
that, all the samples met the MOHE-permitted limits for Cd and Pb
levels, as verified by ICP-MS. Although there were traces of cadmium
and lead, they remained well within the safety recommendations of 3
ppb for cadmium and 50 ppb for lead set by the Malaysian Ministry of
Health.